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Klosen / Slimline / Bifold Doors

White lounge with pink rug and courtyard
Aluminium Doors and Windows
Internal View of Slimline Bifold Doors


Create an aura of space and elegance by installing prestigious slimline bifold doors into your home. Slimline bifold doors are folded open, adding a modern edge to your property with an exquisite, stylish touch. Turn a regular entranceway into one of sophistication and envy.

What Are Slimline Bifold Doors?

Slimline Bifold Doors are installed as a row of floor-to-ceiling doors with large glass panels set in slim aluminium frames. These folding glass doors can be pushed to one side to extend your living areas and create a seamless entranceway between your interior and exterior spaces.

Perfect for both private homes and commercial properties, bifold doors are the latest choice of architects across the UK, optimising views without compromising on insulation or security.
With a versatile range of frame colours and styles, we can provide you with a bespoke design that works with your property aesthetic.

With discreet bi folding designed to offer a 95% opening aspect, aluminium bifold doors don’t just open up your spaces and increase natural light exposure, they ensure you can make the most of your property in its entirety.

When winter time comes you won’t be cold either. Every bi-folding door segment is thermally insulated with snug, weather-tight gaskets that maintain the highest levels of draught-free insulation and noise reduction. Slimline bifold doors are strong, slim and irresistibly stylish.

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Our Customer Reviews

Great Price & Quick Delivery

This company have been amazing and came to our rescue when another company let us down repeatedly over a period of 4 months during our building work. We got a great price, a quick delivery time and the same product but this time with lovely fitters who knew exactly what they were doing. Now we will will have a warm house for christmas HOORAY !! We went for 3 large sliding doors and the quality of the product is excellent . Many thanks to Audrey Cieran and the team I would recommend highly
- Esther Young


Delighted with the product and the service provided by Klosen. The installation team were excellent and very helpful.
- Sara Hyem

Very Happy

We’ve been very happy with the work Klosen recently completed for us. They installed a variety of windows and sliding doors for us on our new build project. All of the information we requested early on was provided promptly and they were great with our architect. Very happy with the end result and the colour they helped us chose.
- Sarah Munton


Senior Architectural Systems

Designed to exceed current and meet future legislation, the PURe bifold door range by Senior Architectural Systems offers unbeatable thermal performance and insulation and comes with a life expectancy of over 40 years. Available in leaf sizes up to 1000mm x 2616mm, these robust designs can take leaf weights up to 100Kg.

These PURe bifold frames are available in two standard stock colours: RAL 9910 and RAL 7016. If you prefer an alternative look, we can also supply a metallic, textured or anodised finish.


This bifold system is perfect if you want multiple doors installed together.


Suitable for a single or double door, this bifold door system works with a swinging mechanism which gives you the option to open out or in.

Senior Architectural System Brochure
SAS Slimline Bifold
exterior view patio with furniture and open windows into dining area


Spanish manufacturer Cortizo has a history dating back to 1972. A world leader in the design and manufacture of aluminium doors and windows, its bifold doors are among the finest on the market in terms of aesthetics, performance and durability. Ideally suited for use in both residential and commercial environments, Cortizo bifold doors have slim sightlines and hidden rollers.

Cortizo Brochure
decking area with garden furniture and patio doors

10 Year Guarantee

We offer a 10 year guarantee on all aluminium profiles and 25 years for the powder coating element

Thermal Efficiency

Stay warm in the winter and cool in the summer whilst cutting down on energy bills

Complete Flexibility

Our team are flexible throughout the entire process, including the design and installation of windows

25+ Years Experience

Klosen have over 25 years experience working with designers, architects and homeowners

Where We Work

We install high-spec aluminium bi-fold doors across Lincolnshire, Cambridgeshire and London. With our Lincolnshire-based showroom, you can see the sophisticated range of designs we have to offer and choose the one that’s right for your building project. From Stamford to Covent Garden, we’re proud to supply luxury bi-fold doors that transform commercial and domestic spaces.

To find out more about the products and brands we supply, simply download our informative brochure. To enquire about any of our slimline bifold door designs and how they could enhance your property, get in touch with our friendly team today or speak to them about all of our options for aluminium doors and windows.

You can also get slimline sliding doors or slimline aluminium windows to go with your doors.


What are bifold door sightlines?

Bifold door sightlines refer to the distance between a pane of glass on one door and the pane of glass on a neighbouring door. It’s basically the width of the two door frames before you reach the glass panel. Slimline bifold doors are favoured for having slimmer frames which reduces the sightline and offers better views and increased levels of natural light.

What is the maximum size for bifold doors?

If you’re choosing one of our Senior Architectural Systems bifold doors the maximum size is 1000mm x 2616mm.

What is a door leaf?

The number of leaves refers to how many doors you have. With slimline bifold doors you can have single, double or multiple leaves.

Get in touch with us today to receive your free quotation!